Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details)

v2.4.0.6
Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Derivatives, Fair Value [Line Items]    
Available-for-sale Securities, Interest-only $ 86,221 $ 48,372
Agency To-be-Announced Securities, Notional Amount, Long 450,000 275,000
Agency To-be-Announced Securities, Notional Amount, Short   850,000
Agency To-be-Announced Securities, Fair Value, Asset 3,967 2,664
Agency To-be-Announced Securities, Fair Value, Liability   (5,652)
Forward Purchase Commitment [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Notional Amount 319,931  
Derivative Asset, Fair Value, Net 604  
Forward Sale Commitment [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Notional Amount   $ 5,202